2. generate a signature. Assemble the request parameters into a string to be signed according to certain rules, and then sign it with a key. The signature algorithm is generally RSA or RSA2.
3. make a request to AliPay. Send the signed request parameters and signature value to Alipay, and wait for Alipay's response.
4. handle AliPay response. According to the results returned by Alipay, judge whether the payment is successful or not, and record relevant information locally.